In the electronics field, non-linear optical properties, conductivity and semiconductivity of various organic compounds have been attracting attention, and various devices using organic substances have been actively developed. Phthalocyanine compounds, porphyrin compounds, fused polycyclic aromatic ring compounds, such as polyacenes and pyrene, arylamine compounds, bisazo pigments and the like, are known as typical examples of organic semiconductor compounds. Properties, such as non-linear optical properties, electrical conductivity and semiconductivity, which are required for using these compounds as organic materials to form devices, largely depend on crystallinity and orientation of each of the materials, and it is important to use highly purified materials in order to fully exploit these properties. However, high purification of these materials has been difficult, because many of compounds having an extended π-conjugated system are susceptible to oxidation in air.
Fused aromatic ring compounds represented by pentacene have been receiving attention in recent years for their electrical conductivity, semiconductivity etc. However, it is very difficult to obtain pentacene of high purity due to its low solubility.
Particularly, it is necessary to form thin films of pentacene in order to use it for various devices, but thin film preparation using a vacuum process etc. increases the production cost. In recent years, there has been developed a method for producing pentacene from a pentacene precursor using the reverse Diels-Alder reaction as a key reaction (WILLEY-VCH Verlag GmbH, “Advanced Materials”, Vol. 11, No. 6, p. 480-483, 1999). However, the conversion to pentacene requires a high-temperature treatment of 170° C. or above and freed high mass components must be removed under a reduced pressure. Conversion to pentacene at a low temperature is also reported (“Journal of American Chemical Society”, Vol. 124, p. 8812-8813, American Chemical Society, 2002), but there is a problem in the stability of the soluble precursor of pentacene.